Numerous types of vehicles are frequently used on terrain where it is difficult for pneumatic tires to operate. Both defense defence vehicles, such as tanks and amphibious vehicles, and civilian vehicles, such as tractors and recreational vehicles, are sometime utilized on terrains which are very soft, for example sand surfaces. Pneumatic tires are not capable of efficient operation on such soft surfaces, as they tend to burrow into the surface, rather than riding across it.
In the past the most popular type of traction band for heavy duty vehicles have been metallic traction surfaces.
Recently, elastomeric endless traction bands have become popular due to an increase in construction and in urban areas, where vehicles having traction bands must drive on the pavement and because there is a demand for vehicle use for low soil compaction farming, and over snow covered, very uneven, or muddy terrain. With the combination of elastomeric technology and a tremendous amount of trial and error, various types of elastomeric traction bands are now available in the industry. They are used on excavators, dump carriers, boring machines, combines, tractors, and the like.
While elastomeric endless traction bands are often desirable since they reduce damage to the terrain, reduce noise and allow access to various types of soil, they do have some drawbacks concerning their installation and removal. Once installed, the traction band is usually carried and maintained in tension by a plurality of rotating elements (wheels, sprockets, etc . . ..) that are connected to the vehicle. The traction bands being maintained in circwnferential circumferential contact with these rotating elements are being driven thereby (or, in the case of trailer-like non-driven vehicles, being supported for rotation thereon).
Metallic traction surfaces which are often formed by a number of individual pieces fastened together can be separated into a single strip thus allowing for easy installation onto the plurality of rotating elements. Elastomeric traction bands on the other hand are usually formed of a single continuous piece, and it is typically difficult and may require special equipment to mount them around the plurality of rotating elements, or remove them when maintenance or access is needed on the. vehicle. This is especially true with traction bands for heavy duty vehicles where the traction bands can weigh a substantial amount.
As elastomeric traction bands have grown more popular it has become apparent that the best way of installing a new traction band involves the removal of one or more of the wheels or other rotating elements from the vehicle. While the removal of the wheel rotating elements allows the traction band to be slid around the drive assembly with more ease, reinstalling the wheel rotating elements still may pose problems.
Elastomeric endless traction bands comprising only one row of lugs on its inner surface have been designed by Rodgers et al. (U.S. Pat. No. 6,296,329) Gleasman et al. (U.S. Pat. No. 6,135,220), Crabb (U.S. Pat. No. 5,312,176), Grawey et al. (U.S. Pat. No. RE37,174) and Burckhartzmeyer et al. (U.S. Pat. No. 5,749,423). The vehicle=s vehicle's plurality of wheel provides a central spacing to receive the lugs of the traction bands, thus ensuring guidance to the band and power transmission, either by friction or by the lugs meshing in a sprocket drive wheel. Since those bands are sometimes used on very muddy or uneven terrains, the lack of a second row of lugs increases the chances of detracking occurrences of the band when lateral forces are too high.
Another typical endless traction band comes with a set of rows of drive lugs that are disposed on the outboard side of the plurality of wheels and one or more rows of central guide lugs, when viewed in a longitudinal direction. Tucker (U.S. Pat. No. 6,129,426) and co-pending patent application by Soucy et al. (U.S. Ser. No. 09/984,307) defines such an endless band. On top of power transmission, the drive lugs provides lateral support which prevents the disengagement of the traction band while the vehicle operates on irregular terrains and in the case of wrong maneuvers from operators. Installing such an endless traction band requires special tools in conjunction with a defined method of operation. The insertion of the protruding rows of drive lugs and guide lugs, which are located on the inner surface of the traction band, on each side and in the central spacing provision of the plurality of wheels represent a source of installation problems, due to the lack of radial space between the vehicle body and the its plurality of wheels.
Yamamoto et al. (U.S. Pat. No. 5,894,900) also proposes an endless traction band to be installed over pneumatic tires. Two rows of lugs on the inner surface of the band provides lateral support. The band can be installed and tightened easily by varying the air level in the tires.
Co-pending U.S. patent application from Deland et al. (Ser. No. 10/202,391) replaces the drive wheel or the tension wheel with a wheel which is made of several parts, when viewed in a lateral direction. When combined with a step by step method, the use of the split wheel ensures an easier installation of the endless band on the vehicle. This invention requires the modification of one of the plurality of wheels, but can work with the same endless band as before.
The present invention sets out to solve the problem associated with the installation or the removal of an elastomeric endless traction band by providing a special configuration of drive lugs and guide lugs on its inner surface. The drive lugs engage in the drive sprocket cavities and fills a double mandate by ensuring power transmission from the engine to the traction band as it offers lateral support on one side of the plurality of wheels on which the traction band is mounted on. Guidance and lateral support of the endless band is provided by the guide lugs.